Hepatitis E Virus Genotype 3 Diversity: Phylogenetic Analysis and Presence of Subtype 3b in Wild Boar in Europe

An increasing number of indigenous cases of hepatitis E caused by genotype 3 viruses (HEV-3) have been diagnosed all around the word, particularly in industrialized countries. Hepatitis E is a zoonotic disease and accumulating evidence indicates that domestic pigs and wild boars are the main reservoirs of HEV-3. A detailed analysis of HEV-3 subtypes could help to determine the interplay of human activity, the role of animals as reservoirs and cross species transmission. Although complete genome sequences are most appropriate for HEV subtype determination, in most cases only partial genomic sequences are available. We therefore carried out a subtype classification analysis, which uses regions from all three open reading frames of the genome. Using this approach, more than 1000 published HEV-3 isolates were subtyped. Newly recovered HEV partial sequences from hunted German wild boars were also included in this study. These sequences were assigned to genotype 3 and clustered within subtype 3a, 3i and, unexpectedly, one of them within the subtype 3b, a first non-human report of this subtype in Europe.